Pituitary FSH Research Articles

Diet-Induced Obesity and Ghrelin Effects on Pituitary Gonadotrophs: Immunohistomorphometric Study in Male Rats.

The close relationship between energy metabolism, nutritional state, and reproductive physiology suggests that nutritional and metabolic disorders can disrupt normal reproductive function and fertility. Considering the importance of leptin and ghrelin effects in regulation of the hypothalamic-pituitary-gonadal axis, the objective of this study was to investigate the influence of obesity and centrally applied ghrelin on immunohistochemical appearance and quantitative morphology of the pituitary follicle-stimulating hormone (FSH) and luteinizing hormone (LH) producing cells in adult male rats. In this experimental study, animals were given two differ- ent diets: normal-fat (NF) and high-fat (HF), for 4 weeks, corresponding to normal and positive energy balance (n=2×14), respectively. Each group was subsequently divided into two subgroups (n=7) receiving intracerebroventricular (ICV) injections of either ghrelin [G, 1 µg/5 µL phosphate buffered saline (PBS)] or vehicle (5 µL PBS, control group) every 24 hours for five consecutive days. Morphometric analyses showed that in HF control group, the percentage of FSH cells per unit volume of total pituitary gland tissue (in μm(3)), i.e. volume density (Vvc), was increased (P<0.05) by 9.1% in comparison with the NF controls. After ICV treatment with ghrelin, volume (Vc) and volume density (Vvc) of FSH cells in ghrelin+NF (GNF) and ghrelin+HF (GHF) groups remained unchanged in comparison with NF and HF controls. Volume of LH cells in HF control group was increased by 17% (P<0.05), but their Vvc was decreased by 8.3% (P<0.05) in comparison with NF controls. In GNF group, the volume of LH cells increased by 7% (P<0.05), in comparison with the NF controls, but in GHF group, the same parameter remained unchanged when compared with HF controls. The central application of ghrelin de- creased the Vvc of LH cells only in GNF group by 38.9% (P<0.05) in comparison with the NF control animals. The present study has shown that obesity and repetitive ICV administra- tion of low doses of ghrelin, in NF and HF rats, modulated the immunohistomorphometric features of gonadotrophs, indicating the importance of obesity and ghrelin in regulation of the reproductive function.

Oral Presentation VIII

ABSTRACT BACKGROUND AND AIMS Activin, a member of the transforming growth factor beta protein family, was originally isolated from gonadal fluids and stimulates the release of pituitary follicle-stimulating hormone (FSH). Activin has numerous functions in both normal and neoplastic cells. Although it was suggested that gonadal tissue is the primary site of activin production, several extragonadal sources have subsequently been identified, including human thyrocytes. METHODS In our study, serum levels of activin A were measured by chemiluminescence, and the expression of receptors of activin A in thyroid tissue was detected by immunohistochemistry in female patients with thyroid papillary cancer [stage I (n = 60), stage II (n = 60), stage III (n = 60), stage IV (n = 60)] and in normal controls (n = 60). RESULTS The serum levels of activin A were no significantly different between patients with thyroid papillary cancer and normal controls as well as different stages. But the expressions of receptors of activin A were greater in patients with thyroid papillary cancer than in normal controls. And the positive rates of receptor expression were significantly more in stage III and IV than in stage I and II. CONCLUSION In conclusion, this study demonstrates that serum levels of activin A undergo no significant changes when thyroid papillary cancer occurs. The thyroid gland is not the predominant source of activin A. The expressions of receptors of activin A were significantly greater in patients with thyroid papillary cancer than in normal controls. And the positive rates of receptor expressions were associated with the severity of cancer. Because activin A may exert negative action on thyrocyte proliferation, it is conceivable that the increase in the receptor of activin A in thyroid papillary cancer might represent a counteracting mechanism.

Evaluation of safety of modified-Danggui Buxue Tang in rodents:immunological, toxicity and hormonal aspects

Ethnopharmacological relevanceRadix Astragali (RA), Radix Angelicae Sinensis (RAS) and Folium Epimedii (FE) are three of the extensively applied herbs among traditional Chinese medicines for gynecological disorders and osteoporosis. A derivative herbal formula—RRF, consisting of the three medicines with a weight ratio of 5:1:5, is derived from a famous Chinese herbal formula—Danggui Buxue Tang (DBT). RRF has shown noteworthy perimenopause ameliorating effect in both ovariectomized rats and natural aging female rats, which might represent a promising candidate for the treatment of perimenopausal disorders. The aim of this study was to evaluate its immunological potential, chronic toxicity and reproductive effects by 26-week repeated daily administration in female rats, in order to optimize its safe use. Materials and methodsThe effect of RRF on immunological function was studied by macrophage phagocytosis, immune organ index, serum immunoglobulin level as well as delayed type hypersensitivity (DTH) in mice. For toxicity assessment, acute toxicity study was performed according to fixed dose procedure with a single oral administration of RRF to mice. In the oral chronic toxicity, 120 female rats were administrated RRF orally in 0, 1100, 4400, or 8800mg/kg/day doses for 26 weeks. Clinical signs, mortality, body weights, feed consumption, haemato-biochemical parameters, organ weights, histopathology and reproductive hormone profiles were examined at the end of the 13- and 26-week dosing period, as well as after the 4-week recovery period. ResultsOral administration of RRF at three doses (282, 564 and 1128mg/kg) significantly increased the indices of phagocytosis K, as compared with prednisone acetate (PR) group (p<0.05 or 0.01). Exposure of RRF dose-dependently boosted circulating serum IgM level (all p<0.01) in response to CRBC in PR-induced mice. Furthermore, RRF treatment elicited a significant increment (all p<0.01) in DNFB-induced DTH response and the immune organ indices in a dose-dependent manner in mice, in parellel to DNFB-induced group. In the single dose acute toxicity and repeated dose 90-day chronic toxicity investigations, no toxic signs/mortality were observed. RRF treatment did not cause any toxicologically significant changes in clinical signs, food consumption, body weight, relative organ weight, hematological parameters, clinical chemistry, gross pathology and histopathology between treatment and control groups. No treatment related gross/histopathological lesions were observed and no target organ was identified. Long-term repeated administration of RRF exerted a significant promotion on serum level of steroid hormone estradiol, progesterone and testosterone release, along with decrease of circulating pituitary follicle stimulating hormone, luteinizing hormone, and prolactin levels in female rats. The No Observed Adverse Effect Level (NOAEL) of RRF was determined to be over 8800mg/kg/day for elderly female rats, a dose that was equivalent to 50 times of human dose. ConclusionThe present investigation demonstrated that RRF possessed appreciable immunopotentiating activity and had a relatively wide margin of safety. Long-term treatment of RRF exhibited estrogenic properties, and retarded certain age-associated degenerations. RRF might have the potential for further development as a safe and effective alternative/complementary to conventional medication in relieving perimenopausal symptoms.

A delay differential equation model of follicle waves in women

ABSTRACTThis article presents a mathematical model for hormonal regulation of the menstrual cycle which predicts the occurrence of follicle waves in normally cycling women. Several follicles of ovulatory size that develop sequentially during one menstrual cycle are referred to as follicle waves. The model consists of 13 nonlinear, delay differential equations with 51 parameters. Model simulations exhibit a unique stable periodic cycle and this menstrual cycle accurately approximates blood levels of ovarian and pituitary hormones found in the biological literature. Numerical experiments illustrate that the number of follicle waves corresponds to the number of rises in pituitary follicle stimulating hormone. Modifications of the model equations result in simulations which predict the possibility of two ovulations at different times during the same menstrual cycle and, hence, the occurrence of dizygotic twins via a phenomenon referred to as superfecundation. Sensitive parameters are identified and bifurcations in model behaviour with respect to parameter changes are discussed. Studying follicle waves may be helpful for improving female fertility and for understanding some aspects of female reproductive ageing.

A modified ultra-long pituitary downregulation protocol improved endometrial receptivity and clinical outcome for infertile patients with polycystic ovarian syndrome.

There are currently various protocols for in vitro fertilization (IVF). For patients with polycystic ovarian syndrome (PCOS), an optimized protocol for the downregulation of pituitary follicle stimulating hormone and luteinizing hormone via gonadotropin-releasing hormone agonist (GnRHa) remains a challenge. In the present study, the primary endpoint of an ultra-long and a conventional long GnRHa protocol for intracytoplasmic sperm injection/IVF treatments of patients with PCOS was retrospectively compared. In the modified ultra-long protocol group, endometrial thickness, morphology, and blood flow were significantly improved, as compared with in the conventional long protocol group. Furthermore, the serum progestogen (P) concentrations and P/estrogen (E2) [(Px1,000/E2)] ratio on the day of human chorionic gonadotrophin administration were significantly decreased in the modified ultra-long downregulation group, whereas the pregnancy and implantation rates were significantly higher. There were no significant differences in the average number of obtained oocytes, good quality embryo rates, cancel rates, fertilization rates, abortion rates, serious ovarian hyperstimulation syndrome incidences, ectopic pregnancy rates or gonadotropin (Gn) dosages between the two groups. These results suggest that the modified ultra-long protocol plus human menopausal Gn medication may be superior to the conventional long protocol, and may lead to improved implantation and pregnancy outcomes for infertile patients with PCOS.

Demonstration of the Coexistence of Duplicated LH Receptors in Teleosts, and Their Origin in Ancestral Actinopterygians.

Pituitary gonadotropins, FSH and LH, control gonad activity in vertebrates, via binding to their respective receptors, FSHR and LHR, members of GPCR superfamily. Until recently, it was accepted that gnathostomes possess a single FSHR and a single LHR, encoded by fshr and lhcgr genes. We reinvestigated this question, focusing on vertebrate species of key-phylogenetical positions. Genome analyses supported the presence of a single fshr and a single lhcgr in chondrichthyans, and in sarcopterygians including mammals, birds, amphibians and coelacanth. In contrast, we identified a single fshr but two lhgcr in basal teleosts, the eels. We further showed the coexistence of duplicated lhgcr in other actinopterygians, including a non-teleost, the gar, and other teleosts, e.g. Mexican tetra, platyfish, or tilapia. Phylogeny and synteny analyses supported the existence in actinopterygians of two lhgcr paralogs (lhgcr1/ lhgcr2), which do not result from the teleost-specific whole-genome duplication (3R), but likely from a local gene duplication that occurred early in the actinopterygian lineage. Due to gene losses, there was no impact of 3R on the number of gonadotropin receptors in extant teleosts. Additional gene losses during teleost radiation, led to a single lhgcr (lhgcr1 or lhgcr2) in some species, e.g. medaka and zebrafish. Sequence comparison highlighted divergences in the extracellular and intracellular domains of the duplicated lhgcr, suggesting differential properties such as ligand binding and activation mechanisms. Comparison of tissue distribution in the European eel, revealed that fshr and both lhgcr transcripts are expressed in the ovary and testis, but are differentially expressed in non-gonadal tissues such as brain or eye. Differences in structure-activity relationships and tissue expression may have contributed as selective drives in the conservation of the duplicated lhgcr. This study revises the evolutionary scenario and nomenclature of gonadotropin receptors, and opens new research avenues on the roles of duplicated LHR in actinopterygians.

Emergence of an Ancestral Glycoprotein Hormone in the Pituitary of the Sea Lamprey, a Basal Vertebrate.

The gnathostome (jawed vertebrates) classical pituitary glycoprotein hormones, FSH, LH, and TSH, consist of a common α-subunit (GpA1) and unique β-subunits (Gpβ1, -2, and -3), whereas a recently identified pituitary glycoprotein hormone, thyrostimulin, consists of GpA2 and GpB5. This paper reports the identification, expression, and function of an ancestral, nonclassical, pituitary heterodimeric glycoprotein hormone (GpH) consisting of the thyrostimulin A2 subunit with the classical β-subunit in the sea lamprey, Petromyzon marinus, a jawless basal vertebrate. Lamprey (l) GpA2, and lGpHβ were shown to form a heterodimer by coimmunoprecipitation of lGpA2 with FLAG-tagged lGpHβ after the overexpression in transiently transfected COS7 cells using a bipromoter vector. Dual-label fluorescent in situ hybridization and immunohistochemistry showed the coexpression of individual subunits in the proximal pars distalis of the pituitary. GnRH-III (1μΜ) significantly increased the expression of lGpHβ and lGpA2 in in vitro pituitary culture. Recombinant lamprey GpH was constructed by tethering the N terminal of lGpA2 to the C terminal of lGpHβ with a linker region composed of six histidine residues followed by three glycine-serine repeats. This recombinant lamprey GpH activated the lamprey glycoprotein hormone receptor I as measured by increased cAMP/luciferase activity. These data are the first to demonstrate a functional, unique glycoprotein heterodimer that is not found in any other vertebrate. These data suggest an intermediate stage of the structure-function of the gonadotropin/thyroid-stimulating hormone in a basal vertebrate, leading to the emergence of the highly specialized gonadotropin hormones and thyroid stimulating hormones in gnathostomes.

Growth hormone, luteinizing hormone, and follicle-stimulating hormone regulation by neuropeptide Y in both sexes of the cichlid fish, Cichlasoma dimerus.

Neuropeptide Y (NPY) is considered the most potent orexigenic peptide, increasing before meal time and during fasting. In teleost, most studies on NPY action upon growth hormone (GH) and luteinizing hormone (LH) were conducted in females or group of animals without sex discrimination. The aim of this study was to evaluate whether NPY modulates the expression and release of GH and gonadotropins in both sexes of Cichlasoma dimerus. By double-label immunofluorescence, we first determined the association between NPY fibers and pituitary cells. In addition, we performed in vitro studies to evaluate the effect of NPY on GH and gonadotropins expression by real-time PCR, and release by Western blot, in males and females separately. Contacts between NPY fibers and GH and follicle-stimulating hormone (FSH)-producing cells were detected, indicating possible functional relationships. We observed an increase in GH release in the culture medium at 2 nM for males (p = 0.043) and 20 nM for females (p = 0.028). Pituitary FSH release was stimulated at 20 nM (p = 0.026) and 200 nM (p = 0.033) for males and females, respectively. Finally, NPY only increased β-LH mRNA expression at 20 nM in females (p = 0.028) and its release at 2 nM (p = 0.049) and 200 nM for males (p = 0.005) and 200 nM for females (p = 0.018). In conclusion, NPY acts as a GH-, LH- and FSH-releasing factor, in a dose- and sex-dependent way.

Role of the serotonergic axis in the reproductive failure associated with aging broiler breeder roosters

Reproductive failure associated with aging is a well-known phenomenon. However, the mechanism by which this failure occurs in broiler breeder roosters is still unclear. A previous study conducted in our laboratory, comparing young and aging broiler breeder roosters, demonstrated an elevation in hypothalamic vasoactive intestinal peptide (VIP) and pituitary prolactin (PRL) gene expression accompanied by a deterioration of gonadal axis function. This resulted in a decrease in semen-quality variables as roosters aged. The objective of this study was to examine the involvement of the serotonergic axis in the age-associated reproductive failure in broiler breeder roosters. Cobb roosters aged 64 wk were divided into 3 groups (n = 20 each): parachlorophenylalanine (PCPA) administration, active immunization against chicken VIP, and controls. At 69 wk of age, each group was divided into 2 equal subgroups: 1 received ovine PRL and the other served as controls. Weekly semen volume, concentration and motility, and plasma testosterone, estradiol, and PRL concentrations were examined. At the end of the experiment, roosters were euthanized, testes were weighed, and hypothalamus and pituitary were removed to assay the expression of genes encoding hypothalamic GnRH-I, pituitary FSH, pituitary LH, hypothalamic VIP, and pituitary PRL. Both PCPA administration and active immunization against chicken VIP significantly increased testis weight, semen volume, sperm concentration, ejaculation grade, plasma testosterone level, and GnRH-I, FSH and LH gene expression compared with controls (P ≤ 0.05). In addition, a decrease in plasma estradiol and PRL concentrations and VIP and PRL gene expression was observed in PCPA- and VIP-immunized birds compared with controls (P ≤ 0.05). Administration of PRL in all groups decreased gonadal axis function and semen-quality variables (P ≤ 0.05). Collectively, these results suggest that the increasing expression levels of the serotonergic axis in aging broiler breeder roosters inhibit proper gonadal function and reproductive performance. This article establishes for the first time the inhibitory role of serotonin on reproduction in aging roosters.

Development of approaches to induce puberty in cultured female sablefish (Anoplopoma fimbria)

Efforts to establish sustainable and efficient aquaculture production of sablefish (Anoplopoma fimbria) have been constrained by delayed puberty in cultured females. This study integrates a series of experiments aimed at gaining an understanding of the reproductive physiology of puberty in female sablefish. We detected transcripts for the dopamine D2 receptor (drd2) in brain, pituitary and ovary of sablefish, and prepubertal females exhibited significantly elevated brain and pituitary drd2 expression relative to wild maturing females. Treatments with sustained-release cholesterol pellets containing testosterone (T) and the dopamine D2 receptor antagonist, metoclopramide (Met), stimulated expression of pituitary luteinizing hormone beta subunit (lhb) and follicle-stimulating hormone beta subunit (fshb), respectively, in prepubertal females, whereas a combination of T and gonadotropin-releasing hormone agonist (GnRHa) had a strong synergistic effect on lhb expression (2000-fold higher than control). Although T induced a significant increase in the maximum ovarian follicle volume, none of the treatments tested stimulated onset of vitellogenesis. Using liquid chromatography/tandem mass spectrometry, we demonstrated that Met stimulated production of T by previtellogenic ovarian follicles in vitro, whereas gonadotropin preparations enhanced 17α-hydroxyprogesterone, androstenedione (A4), T and 17β-estradiol (E2) production. Treatment with T increased production of A4, 11β-hydroxyandrostenedione, 11β-hydroxytestosterone, E2, 11-ketotestosterone, and 5α-dihydrotestosterone (DHT). Interestingly, in the presence of high doses of T the previtellogenic ovary preferentially produced A4 and DHT over any other metabolite. Our data suggest the existence of dopamine inhibition of the reproductive axis in female sablefish. Treatments with Met and T elevated gonadotropin mRNAs in prepubertal females but failed to stimulate the transition into vitellogenic growth, suggesting a possible failure in pituitary gonadotropin protein synthesis/release. Previtellogenic ovarian follicles of sablefish are equipped to synthesize steroids, including those required for vitellogenic growth, and DHT, a steroid hormone whose role in reproduction of fishes remains unknown.

Expression of Bioactive Callithrix jacchus Follicle-Stimulating Hormone in Pichia pastoris

Callithrix jacchus (common marmoset) is a New World primate monkey, used as an animal model in biomedical research. Marmoset-specific follicle-stimulating hormone (FSH) preparation is required to improve superovulation protocols and to develop homologous FSH monitoring assays in these monkeys. In this study, we document the large-scale expression of recombinant marmoset FSH in methylotropic yeast, Pichia pastoris. The recombinant preparation was found to be immunologically active in Western blotting and radioimmunoassay. The preparation displayed receptor binding ability in radioreceptor assay. Based on the receptor binding ability, the yield of fermentation was estimated to be 7.2 mg/L. FSH-induced cAMP assay and estradiol assay revealed that the recombinant hormone is able to induce signal transduction. Both immunological and in vitro biological activity of marmoset FSH was found to be comparable to purified human pituitary FSH, which served as reference hormone for these assays. Thus, the study suggests that a Pichia expression system can be used for large-scale expression of bioactive recombinant marmoset FSH.

The effect of bifenthrin on the dopaminergic pathway in juvenile rainbow trout (Oncorhynchus mykiss)

Bifenthrin is a type I pyrethroid pesticide, which has been shown to increase plasma estrogen concentrations in several fish models. The mechanism of action by which bifenthrin alters 17β-estradiol (E2) is unclear. E2 biosynthesis is regulated through pituitary follicle stimulating hormone, which is directly controlled by hypothalamic gonadotropin releasing hormone (GnRH2). Since dopaminergic signaling significantly influences GnRH2 release in fish, the goal of the study was to determine the effect of a 96h and 2 weeks exposure to bifenthrin on dopaminergic signaling in juvenile rainbow trout (Oncorhynchus mykiss) (RT). Our results indicated that a decrease in dopamine receptor 2A (DR2A) expression was associated with a trend toward an increase in plasma E2 following exposure at 96h and 2 weeks, and a significant increase in the relative expression of vitellogenin mRNA at 2 weeks. DR2A mRNA expression decreased 426-fold at 96h and 269-fold at 2 weeks in the brains of 1.5ppb (3.55pM) bifenthrin treated RT. There was an increase in tyrosine hydroxylase transcript levels at 96h, which is indicative of dopamine production in the brains of the 1.5ppb (3.55pM) bifenthrin treated RT. A significant increase in the relative expression of GnRH2 was observed at 96h but a significant decrease was noted after 2 weeks exposure indicating potential feedback loop activation. These results indicate that the estrogenic-effects of bifenthrin may result in part from changes in signaling within the dopaminergic pathway, but that other feedback pathways may also be involved.

Influence of glycans on biological activities of pituitary gonadotropins, follicle-stimulating hormone and luteinizing hormone

Influence of glycans on biological activities of pituitary gonadotropins, follicle-stimulating hormone and luteinizing hormone

Kisspeptin and leptin in the regulation of fertility

Kisspeptin (KISS1) and its receptor (KISS1R) are important regulators of the reproductive function, along with gonadoliberin (GnRH), gonadotropins (luteinizing hormone (LH) and follicle-stimulating hormone (FSH)), and sex steroid hormones. Mutations of their genes alter sexual maturation. The p.P74S, p.H90D, and p.P110T missense mutations of KISS1 are associated with central precocious puberty (CPP); and the p.G35S, p.C53R, and p.F117L mutations, with delayed puberty and isolated hypogonadotropic hypogonadism (IHH). The p.P196H and p.R386P mutations of KISS1R are also associated with CPP. However, a greater number of KISS1R mutations are associated with IHH, as is the case with p.L102P, p.L148S, p.E232Q, p.R297L, p.Y313H, pX399R, and more complex mutations, such as the 155-bp deletion that removes the acceptor splice site of intron 4 and part of exon 5, a deletion of the GCA triplet in position-2 ...-4 of intron 2, and an ACCGGCT insertion in the same site. The heterozygous compound mutations p.C223R/p.R297L and p.R331X/X399R and the 1-bp insertion 1001_1002insC of KISS1R are similarly associated with IHH. Leptin-dependent activation of KISS1 in hypothalamic neurons was observed in mice and sheep, being especially evident after puberty. Leptin exerts a permissive effect in regulating fertility and facilitate the induction of puberty by hypothalamic KISS1 and GnRH and pituitary LH and FSH, which support the reproductive function during further life.

CN-06 * IS HYPOPITUITARISM CLINICALLY RELEVANT IN GLIOMA PATIENTS? - A CROSS-SELECTIONAL TRIAL IN PATIENTS WITH HIGH-GRADE GLIOMAS

BACKGROUND: The outcome of patients with malignant high-grade glioma (HGG) has improved significantly during the last decade. In most patients the radiation field includes parts of the hypothalamus and/or the pituitary gland, which may cause a complex pattern of neuroendocrine dysfunction. The objective to this cross-sectional study was to evaluate the prevalence of secondary and tertiary hypothyroidism in patients following standard therapy of HGG. METHODS: Serum concentrations of pituitary and peripheral thyroid and sexual hormones were measured in 258 subjects (122 female, 136 male) with HGG. All patients had been treated with standard radio-chemotherapy (radiation up to 60 Gy, followed by adjuvant chemotherapy with temozolomide) up to ten years before testing. RESULTS: TSH was reduced in 22% and increased in 18% of all cases (n = 258). Circulating fT4 and fT3 levels were lowered in 5% and 20%, but increased in 10% and 3%, respectively. With regards to the sexual hormones, we observed an interesting hormonal profile in men (n = 123). Pituitary hormones LH, FSH and prolactin were increased in 64%, 62% and 47% of all men. However, circulating testosterone levels were decreased in 40% of men ≤ 50 years and 16% of men > 50 years. In contrast, LH and FSH concentrations were below the lower reference limit in 75% of women > 50 years, but only in 6% of women ≤ 50 years. Serum progesterone and estrogen levels were lowered in 39% and 36% of women ≤ 50 years and in 43% and 0% of women > 50 years. Of note, 78% of women ≤ 50 years and 78% of women > 50 years featured increased circulating testosterone levels. CONCLUSIONS: Standard treatment for HGG results in multiple changes of the pituitary-endocrine axis. Expecially the finding on increased testosterone concentrations in women is striking and warrants further investigation.

Ancient origins and evolutionary conservation of intracellular and neural signaling pathways engaged by the leptin receptor.

In mammals, leptin acts on leptin receptor (LepR) -expressing neurons in the brain to suppress food intake and stimulate whole-body metabolism. A similar action of leptin on food intake has been reported in the frog Xenopus laevis and in several bony fishes. However, the intracellular signaling and neural pathways by which leptin regulates energy balance have not been investigated outside of mammals. Using reporter assays and site-directed mutagenesis we show that the frog LepR signals via signal transducer and activator of transcription (STAT) 3 and STAT5 through evolutionarily conserved tyrosine residues in the LepR cytoplasmic domain. In situ hybridization histochemistry for LepR mRNA in brain and pituitary showed strong expression in the magno- and parvocellular divisions of the anterior preoptic area (homologous to the mammalian paraventricular nucleus), the suprachiasmatic nucleus, ventral hypothalamus, and pars intermedia and pars distalis of the anterior pituitary. Leptin injection increased phosphorylated STAT3 immunoreactivity in LepR mRNA-positive cells, and induced socs3 and pomc mRNAs. Microarray analysis of preoptic area/hypothalamus/pituitary 2 hours after leptin injection identified leptin-regulated genes that included c-fos, a known leptin-activated gene; pituitary follicle-stimulating hormone subunit β, suggesting an important role for leptin in the reproductive axis of frogs; and B-cell translocation factor 2, which has important functions in neurogenesis. Our findings support that the intracellular signaling pathways and neural substrates that mediate leptin actions on energy balance were present in the common ancestor of modern amphibians and amniotes and have been conserved over 350 million years of evolutionary time.

Calcineurin and CRTC2 mediate FSH and TGFβ1 upregulation of Cyp19a1 and Nr5a in ovary granulosa cells.

Estrogens are essential for female reproduction and overall well-being, and estrogens in the circulation are largely synthesized in ovarian granulosa cells. Using primary cultures of ovarian granulosa cells from gonadotropin-primed immature rats, we have recently discovered that pituitary FSH and ovarian cytokine transforming growth factor beta 1 (TGFβ1) induce calcineurin-mediated dephosphorylation-activation of cAMP-response element-binding protein (CREB)-regulated transcription coactivator (CRTC2) to modulate the expression of Star, Cyp11a1, and Hsd3b leading to increased production of progesterone. This study explored the role of calcineurin and CRTC2 in FSH and TGFβ1 regulation of Cyp19a1 expression in granulosa cells. Ovarian granulosa cells treated with FSH displayed increased aromatase protein at 24 h post-treatment, which subsided by 48 h, while TGFβ1 acting through its type 1 receptor augmented the action of FSH with a greater and longer effects. It is known that the ovary-specific Cyp19a1 PII-promoter contains crucial response elements for CREB and nuclear receptor NR5A subfamily liver receptor homolog 1 (LRH1/NR5A2) and steroidogenic factor 1 (SF1/NR5A1), and that the Nr5a2 promoter also has a potential CREB-binding site. Herein, we demonstrate that FSH+TGFβ1 increased LRH1 and SF1 protein levels, and their binding to the Cyp19a1 PII-promoter evidenced, determined by chromatin immunoprecipitation analysis. Moreover, pretreatment with calcineurin auto-inhibitory peptide (CNI) abolished the FSH+TGFβ1-upregulated but not FSH-upregulated aromatase activity at 48 h, and the corresponding mRNA changes in Cyp19a1, and Nr5a2 and Nr5a1 at 24 h. In addition, FSH and TGFβ1 increased CRTC2 binding to the Cyp19a1 PII-promoter and Nr5a2 promoter at 24 h, with CREB bound constitutively. In summary, the results of this study indicate that calcineurin and CRTC2 have important roles in mediating FSH and TGFβ1 collateral upregulation of Cyp19a1 expression together with its transcription regulators Nr5a2 and Nr5a1 in ovarian granulosa cells.

Inhibin at 90: from discovery to clinical application, a historical review.

When it was initially discovered in 1923, inhibin was characterized as a hypophysiotropic hormone that acts on pituitary cells to regulate pituitary hormone secretion. Ninety years later, what we know about inhibin stretches far beyond its well-established capacity to inhibit activin signaling and suppress pituitary FSH production. Inhibin is one of the major reproductive hormones involved in the regulation of folliculogenesis and steroidogenesis. Although the physiological role of inhibin as an activin antagonist in other organ systems is not as well defined as it is in the pituitary-gonadal axis, inhibin also modulates biological processes in other organs through paracrine, autocrine, and/or endocrine mechanisms. Inhibin and components of its signaling pathway are expressed in many organs. Diagnostically, inhibin is used for prenatal screening of Down syndrome as part of the quadruple test and as a biochemical marker in the assessment of ovarian reserve. In this review, we provide a comprehensive summary of our current understanding of the biological role of inhibin, its relationship with activin, its signaling mechanisms, and its potential value as a diagnostic marker for reproductive function and pregnancy-associated conditions.

Exposure to dexamethasone reduces pituitary volume and gonadotropic cell number in rat fetuses

Overexposure to glucocorticoids during the fetal period induces changes in developmental processes in various fetal tissues. The aim of this study was to investigate the effects of the synthetic glucocorticoid, dexamethasone (Dx), on pituitary volume and gonadotropic cells during a critical period of pituitary development. The effects of Dx on stereological parameters of the pituitary gland and FSH and LH cells were investigated in 19 and 21-day old fetuses. On day 16 of pregnancy, the experimental dams received 1.0mgDx/kgb.w. subcutaneously, followed by 0.5mgDx/kgb.w./day on days 17 and 18 of gestation. The control gravid females received the same volume of saline. FSH and LH cells were stained immunohistochemically by the peroxidase–antiperoxidase method (PAP). In 19-day old fetuses, exposure to Dx caused a significant decrease of pituitary volume, estimated by Cavalieri's principle. Also, the total number of FSH and LH cells per pituitary, determined by physical fractionator counting technique, was significantly reduced. These changes persisted until fetal day 21. Volume densities and numerical densities of FSH and LH cells after exposure to Dx in 19 and 21-day old fetuses remained unaffected. Our results suggest that altered stereological parameters in pituitary gland after exposure to dexamethasone in fetal period could be long-lasting.

Redirecting intracellular trafficking and the secretion pattern of FSH dramatically enhances ovarian function in mice

FSH and luteinizing hormone (LH) are secreted constitutively or in pulses, respectively, from pituitary gonadotropes in many vertebrates, and regulate ovarian function. The molecular basis for this evolutionarily conserved gonadotropin-specific secretion pattern is not understood. Here, we show that the carboxyterminal heptapeptide in LH is a gonadotropin-sorting determinant in vivo that directs pulsatile secretion. FSH containing this heptapeptide enters the regulated pathway in gonadotropes of transgenic mice, and is released in response to gonadotropin-releasing hormone, similar to LH. FSH released from the LH secretory pathway rescued ovarian defects in Fshb-null mice as efficiently as constitutively secreted FSH. Interestingly, the rerouted FSH enhanced ovarian follicle survival, caused a dramatic increase in number of ovulations, and prolonged female reproductive lifespan. Furthermore, the rerouted FSH vastly improved the in vivo fertilization competency of eggs, their subsequent development in vitro and when transplanted, the ability to produce offspring. Our study demonstrates the feasibility to fine-tune the target tissue responses by modifying the intracellular trafficking and secretory fate of a pituitary trophic hormone. The approach to interconvert the secretory fate of proteins in vivo has pathophysiological significance, and could explain the etiology of several hormone hyperstimulation and resistance syndromes.